Process of manufacturing barbituric acid.



= ED TA PaTrEXT OFFICE;

' UTTU '0 L1 ES. 0 1" DA RUSTA D'l, GE RNA N Y.

To all ll'lmm't'l mu y concern: v

Be it known that I, ()"r'ro \VoLFEs, doctor of philosoph a subject of the German Emperor. residing at the. cit of Darinstadt, in the Empire of Germany, have invented certain new and useful lmprovementsin the Process of Manufacturing Barhituric Acids, of which the fol owing is a specification.

I have ascertained that if guanvl-urea is" condensed with cyan derivatives of the following general formula.

' Alkyl C().U..-\lk rl condensation products are obtained which are prohahlv mixtures of several substances for the reason that gnanyl-nrea. is enabled to react m two pscudomeric forms:

. j v (a) \H=-(30-NH c This unsynnnetrical form can be condensed with the above mentioned derivatives to substances of the two following typical formulae:

l1) su p-warm! m I The second symmetrical form:

under the same circumstances condensed to substances of the following typical formula:

A Hit-(2 KB u 1 A y t3..\'ll tru\'= c Alkyl na-c=o The substances of all these three typical formula. when heated with aqueous acids, are easily converted into dialkyl harbituric arids of the well known formula:

the reactions taking probably place in ac- ('UHlilllL'R with the ffllluwlllg formulae:

Specification of Letters Patent.

liters of absolute alcohol.

Patented Aug. 4, 1908;

Appliqafion filed. September 22. 1905. Serial N0. 279,689.

The essential characteristics of the process thus indicatedovill be seen from what is common to the following s )ecific example:

Example, gaanyZ-urea an diethylcyanaceticester.-l3.8 kg. (one molecular proportion) of dried pulverized uanyl-urea hydrochlorid are stirred for 7 ion-is at a temperature of 100 degrees 0. together with 17 (g. (one molecular roportion) of diethylcyanacct-ic ester anti a solution of 6.9'kg. (three atomic proportion) of sodium in 150 The filtrate from the se )arated sodium chlorid is freed from alcoho put into water and neutralized with acetic acid. The precipitate is obtained by centrifugal force. and washed in water. This raw )IUtl'llC-t, comprising scvcral compounds withont being divided into its constituents, is directly heated with sulfuric acid of It is changed into the known diethyl barbituric acid which is then purified by heating the mixture of the said substalltes and saponifving the resulting condensation products y treating these prod ucts'wit-h acids, substantially as described.

2. The process of immufacturing dialkylbarbitm'ic acids consisting in condensing guanyl-urea with dialkyl cyanaeetic esters of the following: general formula:

Alkyl cx by heating the mixture of the said substances and saponifynig the resulting condensation products treating these products with and saponifying vthe resulting condensation acids, substantially as described. 7 product by treating this product with an 3. The process of manufacturing diethyl i acid, substantially as described. barbituric acid consisting in condensing T 5 guanyhurea with diethyl eyanacetic ester of name to this specification in the presence of I the formula: two-subscribing witnesses. Y

OTTO \VOLFES.

c Witnesses: 10. WALTER SCHUMANN,

by heating the mixture of the said substances i K. SEEL.

In testimony whereof I have signed my 15 

